OBSERVATIONS ON HEATING A PIT. 



77 



top of the boiler, and the pipe must incline upwards the whole way 

 from A' to B' about one-third of an inch in nine feet, so that B' is the 

 highest point of the iron pipe, here the air pipe is placed. From B 

 to the top of the reservoir must be an uniform fall; one-sixteenth or 

 one-twenueth of an inch in every foot is sufficient. 



The principal advantages of the apparatus are, that it is applicable on 

 a much smaller scale than any other boiler now in use. That it occu 

 p.es less room, ,s less expensive ; for though its cost in copper, equals 

 or exceeds a common cast iron boiler, yet when the furnace doors 

 and bars, and the expensive setting, and chimney necessary for the 

 alter are taken into account, the economy of this will be apparent 

 It consumes much less fuel, and requires much less attendance as it' 

 may safely be left for three or four hours ; ifonce filled with fuel 



In conclusion, it is perhaps well to observe that any material devia- 

 tions from the proportions given above, will probably be found dis- 

 advan tageous. All cylindrical boilers, with vertical furnace wh ic I 

 have hitherto seen, have been so much too large in proportion TT 

 heigh, that half the heat of the fire went up the "&*£! *** 

 seen this defect ,s cautiously, and 1 believe effectually guarded against 

 A further caut.on also against a common error may not be mispla ed 

 the lowest po„«of the iron pipe, must be above the boile and ,1^ 

 must inchne upwards from the point at which they revive h ho, * 

 <o tke point* which they deliver it to the '£*£ it SfT 

 .« -Inch 1 should be tempted to deviate from this, would b whte , 



2TJ X Z T hlmdred ^ " ,M « ,h ' Whenthe air-p pe „ y 

 placed at the end of ,t furthest from the boiler; and both iron p C 



mchne equally f rom that point towards the bo.ler and reservoir T 



